Born in Houston, Texas, Mixon began his special make-up effects career working on local independent productions, including the 1984 thriller Courage, starring, co-written and produced by Ronny Cox. He eventually became a make-up lab technician and on-set makeup artist on more high profile productions, including The Nightmare on Elm Street Part 2: Freddy's Revenge (1985), The Supernaturals (1986, starring LeVar Burton and Nichelle Nichols), and The Texas Chainsaw Massacre 2 (1986). Perhaps more notably, he worked on 1984's The Terminator (featuring Dick Miller, Brian Thompson, and Paul Winfield) and was part of the "robot team" on the hit science-fiction action film, RoboCop, starring Peter Weller, Robert DoQui, Miguel Ferrer, Kurtwood Smith, Ray Wise, and the aforementioned Ronny Cox.

In 1987, Mixon moved to Los Angeles, California, where he supervised special make-up and creature effects for such projects as Fright Night Part 2 (1988, featuring Brian Thompson), Pet Semetary (1989, starring Denise Crosby), Gremlins 2: The New Batch (1990, starring Zach Galligan, John Glover, Keye Luke, Dick Miller and Robert Picardo), Predator II (1990), and Terminator 2: Judgment Day (1991, featuring Jenette Goldstein). He was also the creature effects supervisor on Stephen King's It (1990); as such, he was responsible for designing, sculpting and applying the make-up for Pennywise character. [1]

More recently, Mixon was the prosthetic make-up artist for The Thing on the 2005 film Fantastic Four and its sequel, Fantastic Four: Rise of the Silver Surfer, based on the characters appearing in Marvel Comics. He was also a key prosthetic artist on X-Men: The Last Stand (2006, starring Kelsey Grammer, Famke Janssen and Patrick Stewart) and was a make-up artist on the 2006 blockbuster, Pirates of the Cairbbean: Dead Man's Chest (featuring Lee Arenberg). In addition, he worked on the Academy Award-nominated prosthetic make-up for the 2007 film Norbit, starring Eddie Murphy.

Mixon's most recent make-up credits include the upcoming films Iron Man (featuring Faran Tahir) and Hellboy II: The Golden Army (starring Ron Perlman). In addition to Star Trek, he is applying make-up effects for the feature film adaptation of the popular anime series Dragonball.